The present invention relates to a golf ball characterized by outstanding flying performance and shot feeling, which has a cover with good scuff resistance and crack resistance.
It has been common practice make a golf ball from a soft core and a hard cover in combination so as to improve its rebound resilience, or shot feeling. The hard cover supplements the rebound resilience of the soft core. The resulting golf ball has improved rebound resilience but the cover cracks after repeated hits.
On the other hand, there have been proposed many ideas of incorporating the cover material with an inorganic filler. See, for example, JP-B 5-73427 and JP-A 6-277312.
These ideas are directed basically to increasing the specific gravity of the cover, thereby increasing the moment of inertia and the flying distance. Their disadvantage is that incorporation with an excessively large amount of inorganic filler impairs the rebound resilience and crack resistance of the ball.
JP-A 2000-5341 discloses a solid golf ball in which the cover material is incorporated with a prescribed amount of inorganic filler, as a reinforcement, having a prescribed specific gravity so that the cover is greatly improved in resistance to cracking due to repeated hits.
Also, JP-A 2001-340494 discloses a golf ball in which the cover is incorporated with a particulate inorganic filler as a reinforcement, which is not necessarily intended to increase the specific gravity, so that the cover has high hardness (larger than 64 in terms of Shore D). The high hardness of the cover reduces the amount of spin and increases the flying distance at the time of driver shot. The adequate difference between the hardness of the core and the hardness of the cover contributes to flying distance and shot feeling as well as crack resistance.
However, existing golf balls still have room for further improvement that complies with golfers' wish for a longer flying distance. The new golf ball to be developed should exhibit higher rebound resilience, softer shot feeling, and better resistance to scuff and crack on the cover.